There are a number of existing clamps for securing electrical wires, conduits or the like to a support.
U.S. Pat. No. 2,972,461 (Balbach) discloses a hose clip 10 having a base 12 and a hose encircling portion 14. The clip is approximately rectangular in shape when in the closed position. At one of the short ends of the rectangle, an integral tab 16 of reduced width allows the clip to be bent around the objects to be retained, hoses 54 and 56. The other short end of the rectangle is comprised of a hook 18 and a flange 22. The flange includes an aperture 24 into which the hook 18 is guided when the clip is closed. Since the hose clip 10 relies on the hoses 54 and 56 to resiliently bias the hook 18 into engagement with the aperture 24, the hose clip 10 is not suitable for retaining bundles of wires or rigid conduits.
U.S. Pat. No. 4,674,720 (Fetsch) discloses a circular pipe saddle which has a detent closure displaced approximately 90 degrees from the point at which the pipe saddle is attached to its support. One end 2 of a saddle body 1 has an inwardly facing detent member 5. The other end 3 of the saddle body 1 has an outward facing J-shaped member having a passage 8 in its curved portion and a detent recess 14 in its long leg portion, the long leg portion of the J-shaped member being formed by a portion of the periphery of the saddle body. Between the passage 8 and the detent recess 14 is a crosspiece 10. When the saddle body 1 is closed, the detent member 5 passes through passage 8, into detent recess 14, and engages crosspiece 10. In the closed position, the detent member 5 is held against crosspiece 10 by the flexible biasing action of end portion 9, the end portion 9 being the short leg of the J-shaped member. Because the end of the detent member 5 projects into the area occupied by the clamped object or objects, it can damage the clamped object or objects.
The loop clamp disclosed in U.S. Pat. No. 2,692,746 (Thomas) is widely used in the aircraft industry. The Thomas clamp is an improved conventional loop clamp 32 which includes a resilient member 14 and a filler block 15 for cushioning the clamped object or objects. The clamp 32 is held in the closed position by the bolt or screw 10 which attaches the clamp to a support 11. A disadvantage of the Thomas clamp (and other conventional loop clamps) is that the resiliency of the clamp tends to hold it in the open position. As a result, the clamp is frequently difficult and time-consuming to install, especially when two or more clamps are stacked and attached to the same support with a single bolt.
The loop clamp disclosed in U.S. Pat. No. 3,376,004 (Goldman) includes means to latch the ear 36 and the foot 38 of the clamp 14 together prior to installation on a support. The latching means, a toggle 50 and a bridge 52, are located on the outer ends of the ear 36 and foot 38. Apertures 46 and 48 in the foot 38 and ear 36, respectively, receive a bolt 60 for securing the clamp to a support.
A disadvantage of the Goldman clamp is that the bridge 52 protrudes above the plane of the upper surface of the ear 36 when the snap clamp is closed, thus presenting a surface that is not perfectly flat. When stacking two or more clamps 32, a washer or other spacer must be placed between them to prevent deforming the ears 36 and feet 38 of the clamps 32 when the bolt 60 is tightened.
Another disadvantage of the Goldman clamp is that the tongue 50 and ear 36 combination is longer than the corresponding ear 18 of the conventional loop clamp 14. In an installation intended for a conventional clamp 14, that additional length may result in interference with adjacent components. Thus, a Goldman clamp 34 is not interchangeable with a conventional clamp 14.
Another disadvantage of the Goldman clamp is that when the clamp 34 is in the latched position, a space exists between the inner ends of the ear 36 and the foot 36. In a clamp which does not include the filler block 42, that space may allow a loose wire to become sandwiched between the ear 36 and the foot 38 when the bolt 60 is tightened, possibly causing an electrical short.
The clamp disclosed in U.S. Pat. No. 4,460,139 (Bochen) is retained in the closed position by the engagement of two tabs 28 with two arresting lugs 30. That engagement is maintained by the bias exerted by the fuel lines 4 on the leg 22 and by the resiliency of the clamping strip 16 at the designated point of bending 18. When used for wire bundles or rigid conduits, it is possible for the clamp 2 to open due to vibration or other physical stress. In addition, the clamp is attached to the support by means of a mounting bracket 6 comprised of a single thickness of the clamp material, which may provide insufficient rigidity.